Nerve Palsies in Limb

Question 1

When are classic brachial plexus lesions seen?

Answer 1

Downward traction - ex. fall on side of neck and childbirth
C5,6 damage - deltoid and shoulder muscles, brachialis and biceps

Question 2

What position does C5 and C6 damage result in?

Answer 2

Erb-Duchenne paralysis - porter’s tip
Arm adducted as deltoid not working
Elbow is extended as biceps not working
Forearm pronated and wrist flexed

Question 3

What damages the upper cords of the brachial plexus?

Answer 3

Upward traction - breech delivery
T1 damage - intrinsic muscles

Question 4

What is the sign of T1 damage?

Answer 4

Klumpke’s palsy - damage to intrinsic muscles giving claw hand

Question 5

Describe the axillary nerve

Answer 5

Posterior cord
Wraps around the neck of humerus
Supplies deltoid and teres minor
Supplies skin over lateral arm - regimental badge area

Question 6

What can cause axillary nerve palsy?

Answer 6

Shoulder dislocation
Fracture surgical neck of humerus

Question 7

How is axillary nerve tested to see if damaged?

Answer 7

Test regimental badge area - reduced sensation
Leads onto deltoid atrophy - cant actively abduct arm

Question 8

Describe the radial nerve

Answer 8

Posterior cord
Supplies triceps in arm
Runs in radial groove of humerus as it passes medial to lateral
Supplies BCR, ECRL and ECRB before dividing into posterior (motor) and superior interosseous nerve (sensory)

Question 9

When do you get radial nerve palsy?

Answer 9

Entrapment
Compression - Saturday night palsy (pressure on nerve for period so zone of reduced circulation)

Question 10

What are the symptoms of radial nerve palsy?

Answer 10

In axilla - loss of elbow extension, wrist extension and sensory changes to forearm and hand
Arm - loss of wrist extension and sensory loss
Forearm - loss of finger extension (PIN)
Wrist - loss of sensation (SRN)

Question 11

Describe the median nerve

Answer 11

Medial and lateral cord
Supplies flexors of forearm and LOAF muscles
Supplies sensation to radial 3.5 digits

Question 12

Describe the carpal tunnel

Answer 12

Floor is carpal bones and roof is flexor retinaculum
Contents - FDS x4, FDP x4, FPL and median nerve

Question 13

What are the causes of carpal tunnel syndrome/

Answer 13

Developmental
Trauma - distal radius fracture
Swellings - ganglion, fibroma and lipoma
Inflammatory - rheumatoid, gout, TB and amyloid
Metabolic - pregnancy, hypothyroidism and mucoploysaccharidoses

Question 14

What is the symptoms of carpal tunnel syndrome?

Answer 14

Nocturnal pain and paraesthesia in part or all of median nerve distribution
Wasting of thenar muscles

Question 15

What is done during examination of carpal tunnel syndrome?

Answer 15

Look - thenar wasting, previous scar and deformity
Feel - sensation
Move - APB power
Special tests - Tinnels (area over tunnel tapped and feel shouting sensations) and Phalens (back of hand together and over time then pain and tingling)

Question 16

How is carpal tunnel treated?

Answer 16

Night splints
Hypothyroidism treatment
Steroid injection - resolves up to 50%
Ultimately need to divide roof of carpal tunnel at level of wrist and release pressure on median nerve

Question 17

Describe the ulnar nerve

Answer 17

Medial cord
No branches in arm
Enters forearm between 2 heads of FCU
Supplies medial half of FDP, FCU and all intrinsic muscles in hand bar the LOAF muscles
Sensation to ulnar 1.5 digits

Question 18

What is cubital tunnel syndrome?

Answer 18

Second most common nerve entrapment
Cubital tunnel between medial epicondyle and olecranon, with fascial bands from FCU roof

Question 19

What is the symptoms of cubital tunnel syndrome?

Answer 19

Patient has numbness on ulnar side of hand and difficulty with fine tasks

Question 20

Describe muscle wasting in ulnar nerve palsy

Answer 20

1st webspace
Guttering between metacarpals
Hypothenar wasting

Question 21

Describe ulnar claw hand

Answer 21

Significant nerve compression
Hyperextension at NCPJ and flexion at IPJs

Question 22

What is ulnar paradox?

Answer 22

A distal lesion has worse clawing than proximal lesion, due to intact long flexors with distal lesion

Question 23

Describe the Froment’s test

Answer 23

Key muscles - adductor pollicis (ulnar nerve) and flexor pollicis longus (median nerve)
If ulnar nerve not working then patient will cheat and use FPL instead of adductor pollicis (thumb flexed)

Question 24

Describe the lateral femoral cutaneous nerve

Answer 24

Roots are L2 and 3
Lies on surface of iliacus muscles and exits pelvis under lateral end of inguinal ligament
Purely sensory to lateral aspect of thigh

Question 25

What does compression of lateral femoral cutaneous nerve cause?

Answer 25

Meralgia paraesthetica

Question 26

What is the treatment of Meralgia paraesthetica?

Answer 26

Common in pregnancy so after will resolve
Injecting tunnel with steroids under US to settle swelling
Then surgery to release tunnel

Question 27

What is the treatment for cubital tunnel syndrome?

Answer 27

Steroid injection
More often tunnel is released during surgery

Question 28

Describe the sciatic nerve

Answer 28

Root L4-S3
Largest nerve in body, main branch of sacral plexus and flat with accompanying artery
Exits pelvis through sciatic foremen below piriformis muscle
Runs deep to gluteus maximus muscles

Question 29

Where does the sciatic nerve supply?

Answer 29

hamstring muscles in thigh (posterior) and part of adductor magnus, and all lower leg and foot muscles via terminal branches

Question 30

When is sciatic nerve at risk of injury?

Answer 30

Posterior dislocation of hip, intra-muscular injection and during surgery (division devastating)

Question 31

Describe the common fibular nerve

Answer 31

Roots - L4-S2
Smaller and lateral branch of the sciatic nerve
Enters foot as winds round fibula neck and splits into superficial and deep peroneal nerve

Question 32

What does injury to common fibular nerve cause?

Answer 32

Foot drop and slapping gait (leg needs lifted higher)
At risk when passes around lateral neck of fibula